The Oregonian/OregonLive analyzed every citation issued in Portland from Jan. 1, 2011 to Dec. 1, 2014, trying to spot trends in how the city’s 56 officers enforce its 89 parking laws.

For some reason, during parking meter hours, the Portland Bureau of Transportation’s enforcement officers write significantly fewer tickets in the mid-afternoon than in the morning and late afternoon.

In fact, the number of citations issued between 2 and 3 p.m. declined 41 percent, when compared to the previous hour.

So, it’s safe to assume that you’re least likely to get a parking ticket at 2 or 3 p.m. on any given day, right?

Not so fast.

Unlike many U.S. cities where parking is free on Sunday, Portland’s enforcers prowl for violators seven days a week. During a typical day, officers rotate through six shifts on week days and five on Saturday.

Dan Aguayo/The Oregonian/OregonLive

But no shifts start or end during the daily ticketing dip, Friedman said. “In fact, enforcement is heavily weighted for mid-day and later in the day,” he said.

Friedman dismissed the possibility that those are the hours when officers prefer to take breaks. Parking Division scheduling doesn’t work that way, he said.

So maybe it’s not an enforcement hole.

A way too logical explanation would be that the number of meter transactions – people buying the clutter-creating time slips displayed in car windows – also falls off a cliff during the early afternoon.

The Oregonian/OregonLive also requested information about every parking-slip purchase during October 2014, the Parking Division’s busiest month in the past four years.

A review of 250,000 of those meter transactions found a corresponding daily plummet in the number of motorists buying parking slips between 2 and 4 p.m.

So, basically the daily dip likely isn’t as much about slack enforcement as it is the hourly migration of drivers in and out of Rip City’s meter districts.

For whatever reason, rain or shine, the early afternoon is the slow period at Portland’s parking meters.

Here are a few more things the city’s parking data revealed:

October is by far the busiest month for parking tickets. During the nearly four-year analysis period, officers wrote 87,045 tickets in October. By contrast, they issued 73,837 in September and 77,856 in November. Friedman said the October spike is likely related to Portland State University students returning for classes in the fall. “There are a lot of first-time students who are parking downtown for the first time and don’t always know the rules,” Friedman said. Also, he noted, October has no free-parking holidays.

February, on the other hand, gives the city the least amount of parking revenue, largely because it has fewer days and includes a parking holiday, city officials said.

The ticketing center of the universe (well, Portland’s parking universe any way) shouldn’t be a surprise: The streets around the PSU campus and the heart of downtown, including Southwest Park Avenue, Third Avenue, Stark Street, Taylor Street and Salmon Street. Those areas have the heaviest concentration of patrols and on-street meter spaces.

After 6 p.m., enforcement begins a slide to 7 p.m., when most of the city’s meters stop accepting payment for the day. Of course, that doesn’t mean motorists who pull into a parking spot at 6:45 p.m. should brush off paying for that 15 minutes of parking, thinking there’s no chance they’ll get ticketed. The data show citations for overtime parking and failure to pay being issued as late 6:58 p.m.

Some districts get far more attention than others. There were days when parking enforcement along the South Waterfront stopped completely after 10:30 a.m. All things considered, that is probably the meter district where you’re least likely to get a ticket.

If there’s a day to try your luck, it’s Sunday. There’s just one shift. PBOT schedules one third of the staff on Sundays compared to the rest of the week. Sunday officers patrol just the metered districts, rather than the whole city. In fact, on Oct. 12, 2014 — a Sunday — the city didn’t issue a single ticket in the Goose Hollow neighborhood and fewer than five in the bustling Pearl District. Although it might appear PBOT was running a skeleton crew of officers to maximize revenue, city officials say that wasn’t the case. Their assumption: More drivers than usual were vigilant about getting back to their cars before time expired.

One last piece of advice: If you’re going to illegally park around Providence Park, don’t do it on the day of a Timbers match.

PBOT officials insist they do not target specific areas guaranteed to generate revenue. The goal, they say, is to use enforcement to promote turnover in the city’s primo parking spaces and to keep vehicles from camping out in the limited number of loading zones serving businesses.

However, at about 5 p.m. on days when the Timbers were playing a 7 p.m. match at home, enforcement suddenly migrates from other parts of the city to neighborhoods around the soccer stadium, the data showed.

“It’s by design, as part of our good neighbor agreement,” said Diane Dulken, a PBOT spokeswoman.

Under the agreement with residents of Goose Hollow and Northwest Portland adopted in 2010, the city is obligated to provide parking enforcement during events at Providence Park, regardless of the cost, Dulken said.

For matches, PBOT asks its parking staff to work overtime. In 2014, Timbers overtime added up to $16,393.44, according to PBOT records.

But the city apparently doesn’t have to worry about those costs eating into its parking revenue.

The Timbers and Providence Park contribute up to $40,000 a year to a spectator facility fund. “The $40,000 is used for PBOT services to fulfill the good neighbor agreement — this includes overtime and items such as barricades,” Dulken said.